The environment of the present invention is a machine stamping operation which uses a continuous feed of sheet material into the die area of a reciprocating stamping machine. More specifically, the stock or material is fed into the stamping area of a press having a stationary die and a die mounted on a vertically reciprocating ram, and as the material is stamped or punched by the reciprocating die, the stamped workpiece is severed from the sheet and dropped into a container as a completed part. This is all conventional.
One of the overriding considerations in a continuous feed press system is the damage to the machine caused by the reciprocating die coming into contact with the stationary die in the absence of material to be punched. This can cause damage to either or both dies and is an undesirable facet of machine operation which requires constant monitoring of the material feeding in order to manually stop the machine in the absence of material. Constant monitoring is required since the absence of material can be caused not only by exhausting the supply of sheet material, but also by a breakdown or jamming of the material feeding apparatus.